• when fed a high-fat diet for 4 months from 8 weeks of age, mutants carrying the paternally-inherited deletion gain less weight than wild-type littermates, with the differences more pronounced in males

• at birth, pups with the paternally-inherited allele are indistinguishable from normal littermates, but beginning at P2, mutants fail to gain weight as effectively as littermates; by 3 weeks, mutant weights are 60% of wild-type male and female weights

• growth rates appear to normalize after weaning, but weight differences persist to maturity in both genders

• unlike other mouse models of Prader-Willi syndrome, mutant pups carrying the paternally-inherited deletion show normal milk intake, righting ability, and muscle tone and strenght after birth and during early postnatal period

• when provided with a high-fat diet, both wild-type and mutant animals reduce their total food intake, but both mutant males and females have lower food intake during the 'day-time' phase relative to wild-type animals (total energy intake is similar to wild-type, indicating that mutants compensate for reduced 'day-time' intake by increasing intake during dark-phase)

• at 6 months of age, both males and females carrying the paternally-inherited deletion allele show increases in daily food intake normalized to body weight (22% or 32%, respectively; at 3 months, males show significant hyperphagia relative to wild-type males, but to a lesser degree than at 6 months, while in females carrying the paternally-inherited deletion allele, daily food intake increases do not reach significance

• when mice are restricted to 80% of their normal food intake levels, wild-type mice gradually lose weight but animals carrying the paternally-inherited deletion allele are better at maintaining their weight (females are significantly better, but males also show improved weight stability compared to wild-type)

• when fed a high-fat diet for 4 months from 8 weeks of age, mutants carrying the paternally-inherited deletion gain less weight than wild-type littermates, with the differences more pronounced in males

• the Snord116 cluster is imprinted and the maternal copy is silenced during oogenesis; only inheritance of the paternal allele with the Snord116 cluster deletion produces the growth deficiency and polyphagia phenotypes in mice

• when offspring have maternal inheritance of the deleted allele, they are normal in size and show normal lifespans